Disazo dyestuff.



more fully,

UNITED STATES PATENT OFFICE.

AUGUST LEOPOLD LASKA AND A RIHUR- ZITSCHER, OF OFFENBACH-ON-THE-MAIN,

GERMANY, ASSIGNORS TO THE CORPORATION OF CHEMISCI-IE FABRIK GRIESHEIM-ELEK'IRON, or FRANKFORT-ON-THE-MAIN, GERMANY.

DISAZO nYEs'rUrr.

No Drawing.-

To all (r/m, it may concern Be it known that we, AUGUST LEOPOLD LASKAand ARTHUR ZITSCHER, bot-h doctors of philosophy and chemists andcitizens of the German Empire, and residents of Offenbach-on-the-Main,in the Grand Duchy of Hesse, Germany, with the post-oilice addresseslVilhelmsplatz 18 and Friedrichstrasse 31, respectively, have inventednew and useful Improvements in Disazo Dyestufls, of which the followingis a specification.

Our invention relates to the production of new disazo dyestuffs, whichmay be obtained by combining the tetrazo compound of tetrachlorobenzidin(NH,:C1:C1:1:2:5) with two molecular proportions of a 1-aryl- 3 methyl 5pyrozolone. v These dyestuffs, having probably the formula:

yield color lakes, which are completely insoluble in oil and'aredistinguished from the-lakesof the dyestufls, described in thespecification of Patent No. 1,001,286, by their greater greenness ofshade. L

In order to illustrate the new' process the following example is given,the parts being by weight: 32.2 parts of tetrachlorobenzidinNH,=o'1=o1=1=2=5 are mixed with 91 parts of hydrochloric acidSpecification of Letters Patent. Patented Dial. 2 1:, 1914. Applicationfiled August 26, 1913. Serial No. 786,654.

of Be. and- 150 parts of water and diazotiaed by addition of 14 parts ofsodium nitrite. Into:this tetrazo solution filtered,

if necessary, is poured a solution, cooled with ice, of 49 parts of1-(2:5)-dichlorophenyl-3-methyl-5-pyrazolone in 56 parts of caustic sodalye of B6. and 400 parts of water while well stirring. The dyestufiseparates in the form of yellow flakes, it is filtered when thecombination is complete and washed neutral. It forms, when dry, anintensively yellow powder, soluble in concentrated sulfuric acid to anorange solution. dyestufi is preferably used in the form of a paste.

This dyestufl has the following formula:

11 The formation of dyestuffs with other 1- For the preparation of lakesthe It yields greenish yellow pigment colors, insoluble in Water and oiland particularly fast to light.

probably aryl-3-methyl-5-pyrazolones may be carried out in the samemanner.

Now whatwe claim and desire to secure by Letters Patent is thefollowing:

1. The process of making disazo dyestufi's especially suitable for thepreparation pigment colors consisting in combining the tetrazo compoundof tetrachlorobenzidin (NH,:C1:C1=1:2":5) with two molecular proportionsof a l-aryl- 3-methyl-5-pyrazolone.

2. As new articles the dyestuffs, having probably the formula whichform, when dry, yellow powders, soluble in concentrated sulfuric acid toan orange solution and giving yellow pigment colors, which are insolublein oil and water and particularly fast to light.

3. The process of making a disazo dyestuif especially suitable for thepreparation of pigment colors consisting in combining the tetrazocompound of tetrachlorobenzidin (NH :C1:C1 1:2:5) with two molecularproportions of the 1- (2 :5) -dichlorophenyl 3 methyl- 5-pyrazolone,

4. As a new article the dycstufl, having probably the formula:

